In-cylinder direct injection internal combustion engine fuel system diagnostic device

摘要

PROBLEM TO BE SOLVED: To early detect with accuracy an excess lean misfire (exhaust temperature abnormal increase) due to fuel pressure reduction by failure of fuel system parts. SOLUTION: The fuel pressure FP supplied to a fuel injection valve is detected (S2), and a duty DUTY of a high pressure regulator is read (S3). As a first misfire condition, it is determined whether or not the fuel pressure EP is not more than a predetermine misfire generation fuel pressure FP1 and not more than a lower limit side failure determination fuel pressure FPMIN set depending on the duty DUTY (S5). As a second misfire condition, determination is carried out whether or not it is within a misfire region in reference to a map defining the misfire region with an engine speed and engine load as parameters. When more than predetermined time is passed where the first and second conditions are satisfied, the exhaust temperature abnormal increase is diagnosed (S8, S9).